1. Field of the Invention
The present invention relates to a coupling part, particularly a coupling plug, for a coupling for pressure medium lines, particularly hydraulic lines, as well as to a coupling having such a coupling part.
2. Description of the Related Art
Such couplings are configured, for example, as plug-in couplings or screw couplings, and guarantee rapid connection and disconnection of two pressure medium lines, particularly hydraulic lines. They have two coupling parts that can be plugged into one another, namely a coupling plug and a coupling cuff. The coupling plug can be inserted into an accommodation opening of the coupling cuff and can be locked into it in releasable manner. If locking takes place by means of a screw connection, for example by means of a locking sleeve, the coupling is referred to as a screw coupling. A plug-in coupling has a retaining ball locking mechanism as the locking means. Each coupling part furthermore has a coupling housing, within which a spring-loaded valve is disposed. In the uncoupled state, the valves are disposed in such a manner that they close off the respective coupling part. When the two coupling parts are plugged into one another, the valves reciprocally open automatically, and when the parts are uncoupled, the valves close automatically, by means of spring force.
Such a plug-in coupling, configured as a quick-release coupling, is known, for example, from EP 1 707 863 B1. The known plug-in coupling has a coupling cuff and a coupling plug having a sleeve-like closing valve, a plunger and a plunger pin. When the two coupling parts are plugged into one another, the plunger, together with the plunger pin, is moved in the opening direction, until the plunger pin makes contact with the closing valve. Then the closing valve is entrained by the plunger pin and the flow channel is opened. In this connection, a spring is disposed around the plunger pin and drives the plunger into its starting position. A further spring directly drives the closing valve into its closed position. This spring is disposed either around the closing valve or behind it.